Method of and apparatus for making metal wire, rod, strip, and the like



B. BRENNAN J. V 1 METHOD OF AND APPARATUS FOR MAKING METAL WIRE, ROD,STRIP AND THE LIKE Filed Aug. 16, 1941 March 20, 1945.

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Patented Mar. 20, 1945 UNITED STATES PATENT OFFICE METHOD OF ANDAPPARATUS FOR MAKING METAL WIRE, ROD, STRIP, AND THE LIKE Joseph B.Brennan, Euclid, Ohio Application August 16, 1941, Serial No. 407,199

8 Claims. (Cl. 22-572) continuation in part of my copending applicationSerial N0. 293,341, filed September 5, 1939.

without requiring excessive pressure or resulting in excessive wear onthe cooling passageway. The discharge of the metal may be assisted by apair of rolls. Preferably the point of discharge produced by expensiveand relatively slow rolling or drawing processes or, in the case of rodsand some of the soft metals, by extrusion at extremely high pressuresthrough dies. Both types of processes require very expensive equipmentand the many operations required add greatly to the cost of the finishedproduct. It isthe general object of my invention to provide a method andapparatus for making such shapes wherein the shapes are formed directlyfrom the molten metal, thus eliminating the many rolling and drawingsteps or the expensive extruding operation heretofore required.

Briefly, a preferred form of my invention contemplates the melting ofmetal ingots (the invention is described herein with particularreference to aluminum, but it is to be understood that my invention isnot limited to any particular metal or alloy) in an apparatus such asdescribed in my copending application aforesaid and comprising acrucible heated by electricity or other means within a pressure chamber.Thus considerable pressure may be exerted on the molten metal withoutapplying destructive forces to the crucible because of the fact that thepressures are equalized on both the outside and the inside of thecrucible. From the crucible the metal is led beyond the interior of thepressure chamber in molten condition preferably through a passageway,the temperature of which can be controlled with a reasonable degree ofaccuracy. The passageway terminates in a cooling zone wherein the metalis solidified, the passage through the cooling zone being of a shape toform the molten metal into the desired configuration. This cooling zone,as distinguished from an ordinary extrusion die, is of considerablelength with the result that the metal enters into the cooling zone whilemolten, and while still in the molten state is caused to assume thedesired cross-sectional shape. As the metal moves along it is gradualcooled, becoming plastic and then solid before its discharge. As mostmetals contract upon solidiflcation and cooling, there is not excessivefriction between the solid metal and the walls of the cooling passagewayso that the metal may be moved through the passageway is shielded by areducing flame, and the metal may be cooled by water or steam shortlyafter it is discharged. Preferably substantial pressures are employed inorder to improve the character or the metal produced by my method, butthese pressures are far below those required for the usual extrusionprocesses. To avoid interruption of the operation of the apparatus, apressure trap is provided for charging the crucible with molten metal.

My method in one sense may be considered as a continuous pressurecasting and drawing method wherein the molten metal may be continuouslyfed into a mold, permitted to solidify in the mold, and the solidifiedmetal continuously withdrawn therefrom. The method is especially adaptedfor the production of wire, the production of rods having shapes similarto those of rods produced by present day extrusion methods, theproduction of tubing, and the production of strip. My methodcontemplates that in the manufacture of material designed for someservices, it will be desirable to subject the wire, rod, tubing or stripproduced by my method to further mechanical reduction as by rolling ordrawing, particularly in instances where it is important to have highstrength in the ultimate product or where very fine wires or thin stripsare desired. However, for many purposes my method will produce metalsuitable for use without further treatment. 1 For example, in theproduction of electrolytic condensers, processes of spraying aluminumare widely used. The spraying step as ordinarily practiced requires theuse of a spray gun in which aluminum wire is melted. This wire should beof high purity and of substantially uniform diameter, but otherwise itsphysical characteristics are not important. For such purposes, my methodand apparatus provides a convenient and economical means of producingaluminum wire which is particularly advantageous today in view of thefact that the production of aluminum Wire by conventional methods is notsufiicient to meet the needs of industry and of national defense.

Referring to the drawingin which a preferred form of apparatus forcarrying out my invention is shown somewhat diagrammatically, Fig. 1 illustrates a transverse section through the entire apparatus; Fig. 2 is asection through the cooling zone as indicated by the line 2--2 of Fig.1; Fig. 3

is a section illustrating the rolls preferably employed to assist inwithdrawing the solid material from the cooling zone as indicated by theline 3-3 of Fig. 1; and Fig.4 is a detail, on an enlarged scale, showingthe pressure seal for the wires that carry the heating current.

As shown somewhat diagrammatically in the drawing, a preferred form ofapparatus may include a pressure chamber and crucible constructedgenerally in accordance with my copending application aforesaid andpreferably comprising a cylindrical pressure chamber l having a bottomportion II and a top closuremember |2 securely bolted thereto as bybolts l4 and I5 respectively, gaskets l6 and i1 being employedto providetight joints. To prevent the pressure chamber from becoming overheated,it is preferably water-jacketed as indicated at l8, l9 and 20, or othersuitable cooling means. may be employed. Water or other cooling liquidmay be supplied to the water jacket members through an inlet pipe 2| anddischarged through the pipe 22. By this means excessive heating of thepressure chamber and consequent weakening thereof may be eliminated.This construction is particularly advantageous in conjunction withmetals or alloys ofhigher melting points such as ferrous materials, forexample, but is not as necessary in conjunction with aluminum or othermetals or alloys of relatively low melting points.

The molten metal to be discharged under pressure is contained in acrucible indicated generally at 25 and supported within the pressurechamber in any convenient manner as by rails 26 resting on upstandingbosses 21 extending from the bottom member I I of the chamber. Thecrucible preferably includes a metallic shell portion 28 having adepending portion 29 extending to the bottom of the container.The-crucible is provided with a lining 30 of refractory material whichis preferably selected so that it will have little, if any, damagingeffect upon the quality of the metal, even' though it may be dissolvedtherein to a slight extent; for example, in conjunction with the meltingof aluminum a lining of aluminum oxide is preferred. The depending neckportion is similarly provided with a lining 3| of the same material, therefractory material preferably projecting slightly above the bottom ofthe crucible as indicated at 32 to prevent foreign matter which mayaccumulate in the bottom of the crucible from being dischargedtherefrom. The molten metal is discharged through the refractory lining3| of the depending neck portion, the opening 33 through the bottommember II and the conduit 34 which leads to the cooling chamber wherethe casting process takes place, indicated generally at 35, The

conduit 34 is also provided with a refractory lining 36, thelining beingmade in a plurality of small pieces, as shown, for convenience ininstallation. At its upper end the member 34 is provided with a flange31 which is bolted to the bottom member H by bolts 38 which also securethe flange 39 of the neck portion 29 in place. Suitable gaskets may beused to prevent leakage between the flanges and the bottom portion.

The crucible may be heated by any convenient means such as by inductionheating or the resistance heating coils indicated diagrammatically at 40and 4| and disposed between the refractory lining 30 and the metallicshell 28. The lead-in wires 42 and 43 pass through the wall of thepressure chamber In, the arrangement shown in Fig.

ing employed to prevent the escape of gas under pressure around thelead-in wires and from the container. To control the temperature of themetal durin its passage through the discharge conduits, separate heatingcoils 44 and 45,- each provided with individual lead-in wires, areemployed. Preferably the heating current for these coils isindependently controllable so that the temperature of the crucible canbe controlled by the coils 40 and 4|, the temperature of the initialportion of the discharge conduit may be controlled by the coil 44 andthe temperature of the end portion of the discharge conduit may becontrolled by the coil .45. The heating effect of the several coils maybe regulated by means of conventional rheostats or other similar devicesnot shown.

While the metal may be melted in the crucible, it is more convenient tomelt the metal in another furnace and supply the molten metal to thecrucible so that the crucible can be intermittently charged with moltenmetal without interrupting the discharge of metal under pressuretherefrom. To this end, I have provided the charging mechanismassociated with the upper portion of the pressure chamber. Thispreferably comprises a funnel shaped member 50 provided with arefractory lining 5| and adapted to receive molten metal from anotherfurnace or ladle. The member 50 leads to a valve 52 which controlscommunication with the enlarged chamber 53, also having a refractorylining 54, and communicating through valve 55 with the con duit 56 whichis adapted to discharge into the crucible 25. The conduit 56 has alining 5! cl refractory material extending through an opening 58 in thetop closure member I2 and the conduit and valve member 55 are providedwith flanges 59 and 60, respectively, which are bolted together and tothe member |2 'as by bolts 6|, gaskets of other suitable packing meansbeing provided to prevent the escape of gases under pressure between therespective flanges and the surfaces of the member l2.

In operation the valve 55, shown open in the drawing, is normallyclosed. When it is desired to charge the crucible 25, the valve 52 isopened and a charge of molten metal poured through the funnel 50 intothe chamber 53. Then air or other suitable gas under pressure isadmitted to the chamber 53 above the level of molten metal thereinthrough the pipe 52 which is provided with a suitable pressure gauge 63and control valve 64. The gas is admitted until the pressure in thechamber 53 equals or slightly exceeds the pressure in the large pressurechamber III, which is indicated by gauge 65. Thereupon the valve 55 isopened and the molten metal in the chamber 53 is discharged into thecrucible 25. Because of the relatively small size of the pressurechamber 53, it is unnecessary to balance the fluid pressures on theinside and outside of the chamber as the chamber walls may be made ofsufficient strength to resist the internal pressures. Further, themolten metal remains in the chamber for only a short time and themetallic outer walls havean opportunity to cool in between chargingoperations. By this means, molten metal may be discharged continuouslyfrom the crucible 25, it being unnecessary to interrupt the operation inorder to replenish the supply of metal within the crucible.

Depending upon the metal employed and the type of material beingproduced, the pressures within the pressure chamber III and on themolten metal within the crucible 25 may be varied from moderatepressures of the order of one or two hundred pounds per square inch torather high pressures on the order of twelve hundred or fifteen hundredpounds per square inch. By reason of the fact that the pressures areapplied equally on the inside and outside of the crucible, nodestructive forces are imposed on the crucible and thus the highpressures can be handled with safety.

The metal under pressure is discharged through the conduits heretoforedescribed into the discharge zone indicated generally at 35 whichconstitutes a separate unit bolted to the flange 61 at the end of theconduit 35. It i in this unit that the metal is given its desired shapeand where the solidification takes place. be termed the cooling, castingor extruding unit and comprises an inner passageway or die 18 which hasthe cross-sectional shape throughout the greater portion of its lengthof the ultimate product, in the present example a round wire beingillustrated, and which is provided with a flared portion I9 forconnection with the end of the conduit 36. The member 18 is surroundedby a reinforcing member 80 and the temperature of the members 18 and 88is controlled by immersing them in a bath of molten material having amelting point suitable for the purpose. In conjunction with theproduction of aluminum wire, I prefer to employ a bath of molten leadindicated at 8|, the lead being heated by a suitable electric heatingcoil 82. The molten lead provides a means for accurately controlling thetemperature in the casting zone and avoiding abrupt changes intemperature. By this means the temperature can be controlled andcorrelated with the speed of discharge so that the liquid metal flowingthrough the member I8 will congeal and become plastic and then solidafter it has been given the desired cross-sectional shape but before itis discharged from the end of the member 18. The passageway 18 may be ofuniform cross-section throughout, or it may be tapered slightly inaccordance with the shrinkage characteristic of the metal.

By so controlling the temperature, the crosssectional shape can beformed without requiring excessive pressures and, inasmuch as the member18 is of considerable length, as distinguished from a die of the typeused in ordinary extrusion operations, slight variations in temperaturewill not prevent the metal from solidifying within the member 18 so thatit can be withdrawn, for example, by the rolls 83 disposed closelyadjacent the discharge end of the member 18. As shown in Fig. 3, therolls 83 are provided with grooves conforming to thedesiredcross-sectional contour of the discharged wire and, if desired, themetal can be discharged from the die member 18 at an elevatedtemperature while it is still in a somewhat plastic condition, in whichcase the rolls may be used to effect a further reduction incross-sectional area or final shaping of the material. If desired, themetal, while still hot, may be drawn through a die (not shown) disposednear the point of discharge to work, size or reduce the extrudedmaterial.

As noted above, under some conditions rather high pressures may berequired in carrying out the continuous casting operation and,therefore, it is important that effective seals be produced where thewires 42 and 43 pass through the walled pressure chamber I0. To thisend, I have pro- This mayvlded the structure shown in Fig. 4 of thedrawing and comprising a water jacketed tube securely bolted to the wallof the chamber II as by bolts 86, a gasket; 81 being employed to preventleakage between the tube and the walled pressure chamber. The tube maybe cooled by water or other suitable cooling medium passing through thewater jacket space 88 and being supplied to the water jacket through thepipe 88,

the liquid being discharged from the jacket through the pipe 90.

The wire 42 passes through the tube 85 and is insulated therefrom bybeing encased within a tube of a heat resisting insulating material 9|.This material may be a suitable plastic insulation such as a Bakelitecomposition, or vitreous materials such as glas may be employed. Theinsulating material, whatever it is, is sealed to the wire so that thegas under pressure within the container cannot leak between the wire 42and its sheath of insulating material 9|.

To prevent leakage between the tube 85 and the sheath of insulatedmaterial 8|, any suitable packing means may be employed, this beingdisposed adjacent the outer end of the tube away from the pressurechamber, a simple and effective construction comprising a Packing glandmember 92 having a flange 93 which is bolted to the flange 94 of thetube 85 by a number of bolts 95. The interior of the packing gland isfilled with packing material 96 which may be compressed by the bolts 85.

By this arrangement a sturdy and effective seal can be made between thewires and the wall of the pressure chamber. The wire itself is sealedwithin a sheath of insulating material and the seal between theinsulating material and the tube is made in a zone spaced away from thepressure chamber so that all of the parts, including the wire, thesheath of insulating material, the tube, the packing gland and thepacking material may be maintained at reasonably low temperaturesregardless of the temperature within the pressure chamber. Thus, as thetemperature where the actual seal is made is fairly low and may be keptquite uniform, differences in coefflcients of expansion of the sheathmaterial involved will not cause any difficulties and an effective sealcan be made.

To summarize the operation of the apparatus and the steps of the method,the crucible 25 may be charged with a molten metal through the chargingmechanism disposed above the pressure chamber. The heating currentsupplied to the coils of the crucible is regulated to maintain themolten metal at the desired temperature above its melting point and gaunder pressure is admitted through the tube 9'! until the desiredpressure indicated on the gauge 98 is reached. Under thesecircumstances, the molten metal is forced outwardly through the conduit8| into the cooling or casting unit 35. The temperature of the metal asit flows through the conduit may be regulated by the various heatingcoils 44 and 45.

The metal, while in the liquid state, i caused to take its desiredcross-sectional shape, the section being reduced by the tapered portion18 of the conduit 18. Thereafter, the fluid pressure exerted upon themetal in the crucible causes it to flow along the conduit 18 withoutsubstantial change in cross-sectional shape, except for shrinkage andduring the time that the metal is flowing through the bore of the member18 the metal is cooled sufficiently to cause it to become either plasticor solid, as desired. The cooling of the metal is controlled byimmersing the conduit 18 in a cooling bath, the temperature of which maybe regulated as by the electric heating coil 82.

After the material has become solidified or at least plastic to theextent that it can be handled, it is withdrawn from the conduit 18, aflame of reducing character 99 preferably being employed to preventoxidation at this point. Thereafter, the material is passed between therolls 83 which may function either to merely withdraw the metal from theconduit I8, or, in addition, to efiect some additional working of themetal. In this last arrangement, the metal may be discharged from theconduit 18 while in the plastic rather than solid state, or at least ata temperature where it may be worked readily. From the rolls 83 themetal is discharged onto any suitable run-out table or wound on a reelor otherwise suitable handled. A conveyor roll I may be employed tosupport the metal before the reeling operation and, if desired, themetal after passing between the rolls 83 may be cooled by jets of water,steam or other medium indicated at lill.

In operation, the pressure within the pressure chamber is correlatedwith the cross-sectional area of the shape being produced and thefriction through the member 18 so that the metal will be forced throughthe member 18 at the desired speed. The speed and temperature, further,must be correlated so that the metal will be cooled and solidifiedduring its passage through the member 18 after the metal has been giventhe desired cross-sectional shape, so that the metal may be withdrawn bythe rolls 83 without breaking the wire, rod, strip, or the like, beingproduced. Because of the comparatively great length of the bore of themember I8, the speeds and temperatures do not need to be controlled withan exceptionally high degree of accuracy for variations will merelycause differences in the points where the solidification of the metaltakes place, which variations do no harm so long as the metal becomessolid within the uniform or slightly tapered bore of the member 18. Thepressures, speeds and temperatures in the cooling may vary, dependingupon the materials involved and the cross-sectional area and shape ofthe ultimate product.

In the foregoing specification, I have disclosed a preferred form of myinvention both as to method and apparatus. Various modifications in bothmy method and apparatus may be made without departing from the spiritand scope of my invention. Accordingly, it is to be understood that mypatent is not limited to the preferred form described in the foregoingspecification or in any manner other than by the scope of the appendedclaims when given the range of equivalents to which my patent may beentitled.

I claim:

1. In an apparatus of the type described, a pressure chamber, means forcooling the pressure chamber, a crucible disposed within said pressurechamber, means for supplying a gas under greater than atmosphericpressure to said pressure chamber to force molten material out of saidcrucible, means for heating said crucible, means for charging saidcrucible from a supply at a lower pressure without releasing the'pressure within said pressure chamber, and a conduit extending from theinterior of said crucible to the exterior of said pressure chamber forcontinuseparately controllable heating means for said crucible and saidconduit, said conduit terminating in a section having a cross-sectioncorresponding to the cross-section of the material to be produced, meansfor cooling said section to solidify metal therein, and a pair of rollsdisposed adjacent the end of said section for withdrawing solidifledmetal therefrom.

3. An apparatus for forming metal rod, wire. strip and the likecomprising a crucible for containing molten metal, means for applyinggas pressure to the surface of the metal in the crucible, a conduitleading from the crucible for discharging molten metal under pressuretherefrom, separately controllable heating means for said crucible andsaid conduit, a die adapted to receive molten metal from said conduit,said die having a flared mouth portion connected to said conduit and anelongated ope -ended portion having substantially the cross-sectionalshape of the finished product, and means for cooling said elongatedportion comprising a bath of molten metal surrounding said elongatedportion.

4. In an apparatus of the type described, a pressure chamber, means forcooling the pressure chamber, a crucible disposed within said pressurechamber, means for supplying a gas under greater than atmosphericpressure to said pressure chamber, means for charging said cruciblewithout releasing the pressure within said pressure chamber, and aconduit extending from the interior of said crucible t0 the exterior ofsaid pressure chamber for discharging the contents of said crucibleunder pressure of said gas, separately controllable heating means forsaid crucible and said conduit, said conduit said conduit terminating inan open-ended section having a cross-section corresponding to thecross-section of the material to be prod and means for cooling saidsection to solidify metal therein.

5. In an apparatus of the type described, a pressure chamber, a crucibledisposed within said pressure chamber, means for supplying a gas undergreater than atmospheric pressure to said pressure chamber, means forcharging said crucible without releasing the pressure within saidpressure chamber, and a conduit extending from the interior of saidcrucible to the exterior of said pressure chamber for discharging thecontents of said crucible under pressure, separately controllableheating means for said crucible and said conduit, said conduitterminating in an open-ended section having a crosssection correspondingto the cross-section of the material to be produced, and means forcooling said section to solidify metal therein.

6. In an apparatus of the type described, a pressure chamber, means forcooling the pressure chamber, a crucible disposed within said pressurechamber, means for supplying a gas under greater than atmosphericpressure to said pressure chamber, means for heating said crucible,means for charging said crucible without releasing the pressure withinsaid pressure chamber, and a conduit extending from the interior of saidcrucible to the exterior of said pressure chamber for discharging thecontents of said crucible under pressure, said conduit terminating in anopen ended section having a crosssection corresponding to thecross-section of the material to be produced, and means for cooling saidsection to solidify metal therein.

'7. An apparatus for forming metal rod, wire, strip and the likecomprising a crucible for containing molten metal, means for applyinggas pressure to the surface of the metal in the crucible, a conduitleading from the crucible for discharging molten metal under pressuretherefrom, separately controllable heating means for said crucible andsaid conduit, and'a die adapted to receive molten metal from saidconduit, said die having a flared mouth portion connected to saidconduit and an elongated, open-ended portion having substantially thecross-sectional shape of the finished product, and means for coolingsaid elongated portion.

8. The method of making metallic rod, wire, strip and the like, whichincludes the steps of continuously discharging molten metal from acrucible by gas pressure, intermittently charging the crucible withmetal from a supply at substantially atmospheric pressure withoutsubstantially affecting the discharge of metal under pressure therefrom,continuously conducting the discharged metal under pressure into acooling zone, causing the metal, while in the molten state, to take thedesired cross-sectional shape in said cooling zone, cooling the metal insaid cooling zone and causing the metal to substantially solidify insaid cooling zone. and continuously discharging the metal therefrom.

JOSEPH B. BRENNAN.

